In general, a driver monitoring apparatus takes an image of a driver's face and recognizes an eye opening degree, an eye direction and a face direction of the driver by analyzing the image of the driver's face. The driver monitoring apparatus further monitors whether the driver drives properly, such as whether the driver keeps his eyes on the road and whether the driver does not fall asleep at the wheel, based on a result of recognition. Such a driver monitoring apparatus is described in JP4725254B2, for example.
In such a monitoring apparatus, when it is determined that the driver falls asleep at the wheel or drives inattentively, a warning sound is generated to alert the driver.
A conventional driver monitoring apparatus is optimized to each type of vehicle. However, different types of vehicles will have different widths, and hence a reference to determine an inattentive drive will be different depending on types of vehicles. Therefore, if the conventional driver monitoring apparatus optimized to one type of the vehicle is equipped to another type of vehicle, the conventional driver monitoring apparatus will not monitor the driver properly.
For example, it is proposed to determine an inattentive drive in left and right directions based on a driver's eye direction. When an angle of the driver's eye relative to a frontal direction is greater than a reference angle, which is defined between the frontal direction and an eye direction that the diver looks at a side mirror, that is, when the driver's eye direction moves in a left or right direction over the reference angle, the inattentive drive is determined. However, the reference angle is different depending on the width of the vehicle. Therefore, if the driver monitoring apparatus optimized to one type of vehicle is equipped to another type of vehicle, the inattentive drive will not be determined properly. As a result, a warning will be given each time the driver looks the side mirror due to the reference angle being too small, or a warning will not be given even if the driver's eye direction moves in a left or right direction over the side mirror.
Also, the similar drawbacks will arise when a driver's seating position is different even in the same type of vehicles.